TSV Buffering Structures to Prevent Metal Gate Residue and Arcing
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Solution Overview
Problem
The formation of through silicon vias (TSVs) in semiconductor devices can lead to issues such as metal gate residue and arcing due to the presence of conductive materials in dummy devices, which can damage fabrication tools and affect the integrity of the device structure.
Innovation Solution
The introduction of buffering structures, such as polycrystalline fins, is employed to prevent incomplete removal of conductive materials during the continuous poly on oxide definition process, thereby preventing metal gate residue and arcing, while guard rings provide protection against moisture and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive materials are present in dummy devices during TSV formation, then device functionality is maintained, but metal gate residue and arcing occur causing tool damage and structural integrity issues
Solution Approach 1:
The patent removes conductive materials from dummy devices in the TSV region by implementing a selective removal process. The method extracts only the necessary conductive elements while leaving functional devices intact, thereby eliminating the source of metal gate residue and arcing problems without compromising overall device functionality.
Solution Approach 2:
The patent applies different material properties to different regions: functional devices retain their conductive materials while dummy devices in the TSV region have conductive materials removed. This local differentiation allows the system to maintain functionality where needed while preventing harmful effects in specific areas through selective material presence or absence.
2Productivity
If continuous poly on oxide definition process is used, then TSV formation is accelerated, but incomplete removal of conductive materials occurs leading to process non-uniformity
Solution Approach 1:
The patent divides the conductive material removal process into multiple sequential steps with different etchants. The first etching step removes conductive materials from dummy devices, followed by a second step that completes the removal and ensures uniformity. This segmented approach maintains high productivity while achieving complete and consistent material removal throughout the structure.
Solution Approach 2:
The patent performs preliminary removal of conductive materials from dummy devices before final TSV completion steps. By anticipating and addressing potential incomplete removal issues in advance through multiple etching steps, the process ensures uniformity is achieved before subsequent fabrication steps occur.
3Reliability
If guard rings are added to protect against moisture and stress, then device integrity is improved, but device complexity increases
Solution Approach 1:
The guard rings serve multiple functions simultaneously: they provide mechanical stress relief, act as moisture barriers, and function as electrical isolation structures. By combining these protective functions into a single structural element, the patent improves device integrity without proportionally increasing complexity, as the same structure delivers multiple protective benefits.
Data Source
AI summary
Embodiments of the present disclosure provide a method for forming TSV structures. In some embodiments, buffering structures are formed adjacent dummy devices in the TSV region. By introducing buffering structures adjacent the end gate structures of the dummy device in the TSV region, residual metallic material may be eliminated, thereby, avoiding arcing in fabrication of TSV structures.